Mohammed Shabir, 45, of Alice Street, Keighley, was being held in police custody ahead of a trial on November 17, 2025.
It was listed as a joint trial with co-defendants Calum Sunderland 26, of Calton Street, Keighley, and Sharaz Ali, 39, of no fixed abode.
The upcoming trial related to the alleged murders of Bryonie Gawith, 29, Denisty Birtle, nine, Oscar Birtle, five, and 22-month-old Aubree Birtle, who all died following a blaze at their home in Westbury Road, off Cooper Lane, in the early hours of August 21 last year.
Shabir pleaded not guilty to their murders as well as pleading not guilty to the attempted murder of Antonia Gawith, Bryonie’s sister.
The Prison Service has since confirmed that Shabir died at HMP Leeds on Wednesday, September 24.
The Prisons and Probation Ombudsman is now set to investigate his death.
A Prison Service spokesperson said: “Mohammed Shabir died on 24 September 2025 at HMP Leeds.
“As with all deaths in custody, the Prisons and Probation Ombudsman will investigate.”
The Crown Prosecution Service has since confirmed to the T&A that a mention hearing is scheduled for October 20 at Bradford Crown Court.
At a brief hearing in July, the Honourable Mr Justice Nicholas Hilliard confirmed that the three men would face a joint trial, having previously set the November 17 trial date.
He extended the custody time limits for all three to November 19 and remanded them in custody.
Family tribute to beloved mum and children
Ms Gawith died at the scene of the fire, and the three children died from their injuries in hospital.
Following the tragedy, there was an outpouring of love throughout the local community.
Tributes left for Bryonie and her children(Image: Newsquest)
The family of Bryonie and her children released a statement in tribute to them.
It read: “Our B was the life and soul of the party.
“Music was a big part of her life – she loved music , singing and dancing.
“She would always be singing and dancing with Chuch, Oggy and Strawberry.
“B was always a really happy, joyful, bubbly, beautiful woman, who cared for everyone and was loved by everyone.
“Her kids were everything to her, her whole life.
“Oggy had the cheekiest smile – he was cheeky but he was a shy boy.
“Strawbs was shy and bashful with big blue eyes and blonde hair, and Chuch was a beautiful, confident, outgoing and creative young girl.
“We are still trying to comprehend what has happened to our beautiful family.
“No words can describe how we are feeling and no words could ever make up for the profound loss we are now faced with.
“We are overwhelmed and grateful for all the support and kind words we are receiving, but we ask as a family if we can be given the respect and privacy so we can try to come to terms with the unimaginable sadness and grief of this tragic loss of our beautiful family.
“Also our thoughts and support are for the father of our three babies.
“Please allow him peace to grieve and come to terms with the loss of his family.”
Trial in November
Ali, who was arrested at the scene of the fire and suffered serious injuries, was initially not expected to survive.
He was charged with murder in March after making a “marked improvement” and being found fit to stand trial by doctors, earlier hearings were told.
West Yorkshire Police previously confirmed he was the ex-partner of a woman who was visiting the family.